The invention relates to methods and equipment for implementing multiple calls in a telecommunications network. The invention will be described in connection with mobile telecommunications networks, especially so-called third generation (3G) mobile communications systems. However, the invention is also applicable in wired networks. 3G mobile systems, such as UMTS (Universal Mobile Telecommunications System), are being standardised by the UMTS Forum and the European Telecommunication Standard Institute (ETSI). The current state of UMTS is defined in references 1 to 4. It has been suggested that future 3G systems permit multiple simultaneous calls to/from a single mobile station. In other words, mobile stations will have multiple independently-controlled traffic channels.
A problem with the prior publications related to 3G systems is that handling of multiple calls is only specified on a “should-be possible” level. In other words, the prior publications almost completely ignore the management details of multiple calls to/from a single mobile station. In a second generation (2G) system, such as GSM, there is one situation where a mobile station may have two calls. Such a situation may arise if the subscriber has a supplementary service (SS) called Call Hold (CH). However, a 2G mobile station does not have multiple independently-controlled traffic channels, and in a CH situation, only one call can be active and the other one is put on hold. Even in so-called high-speed data transfer, a mobile station uses several time slots but all the time slots are assigned to a common traffic channel.